This invention relates to the field of vaso-occlusive devices. More particularly, it relates to a three-dimensional vaso-occlusive device made up of a plurality of non-overlapping loops.
Vaso-occlusion devices are surgical implements or implants that are placed within the vasculature of the human body, typically via a catheter, either to block the flow of blood through a vessel making up that portion of the vasculature through the formation of an embolus or to form such an embolus within an aneurysm stemming from the vessel. One widely used vaso-occlusive device is a helical wire coil having windings which may be dimensioned to engage the walls of the vessels. Other less stiff helically coiled devices have been described, as well as those involving woven braids.
For instance, U.S. Pat. No. 4,994,069, to Ritchart et al., describes a vaso-occlusive coil that assumes a linear helical configuration when stretched and a folded, convoluted configuration when relaxed. The stretched condition is used in placing the coil at the desired site (by its passage through the catheter) and the coil assumes a relaxed configurationxe2x80x94which is better suited to occlude the vesselxe2x80x94once the device is so placed. Ritchart et al. describes a variety of shapes. The secondary shapes of the disclosed coils include xe2x80x9cflowerxe2x80x9d shapes and double vortices. A random shape is described, as well.
Other three-dimensional vaso-occlusive devices have been described. U.S. Pat. No. 5,624,461 to Mariant describes a three-dimensional in-filling vaso-occlusive coil. U.S. Pat. No. 5,639,277 to Mariant et al. describes embolic oils having twisted helical shapes and U.S. Pat. No. 5,649,949 to Wallace et al. describes variable cross-section conical vaso-occlusive coils.
U.S. Pat. No. 5,334,210 to Gianturco, describes a vascular occlusion assembly comprising a foldable material occlusion bag and a filled member, for example, a helical coil with a J-hook on the proximal end. The bag expands to form a diamond shape structure and the filler member inside the bag is forced into a convoluted configuration as it is advanced into the cavity of the foldable bag.
Implantable devices using variously shaped coils are shown in U.S. Pat. No. 5,527,338 to Purdy. Purdy described a multi-element intravascular occlusion device in which shaped coils may be employed. U.S. Pat. No. 5,536,274 to Neuss shows a spiral implant which may asume a variety of secondary shapes. Some complex shapes can be formed by interconnecting two or more of the spiral-shaped implants.
Spherical shaped occlusive devices are described in U.S. Pat. No. 5,645,558 to Horton. Horton describes how one or more strands can be wound to form a substantially hollow spherical or ovoid shape comprising overlapping strands when deployed in a vessel. Notably, the device as deployed must assume a substantially minimal energy configuration in which the loops making up the spherical shape overlap with (n+1) circumference length at a minimum.
Vaso-occlusive coils having little or no inherent secondary shape have also been described. For instance, co-owned U.S. Pat. Nos. 5,690,666 and 5,826,587 by Berenstein et al., describes coils having little or no shape after introduction into the vascular space.
A variety of mechanically detachable devices are also known. For instance, U.S. Pat. No. 5,234,437, to Sepetka, shows a method of unscrewing a helically wound coil from a pusher having interlocking surfaces. U.S. Pat. No. 5,250,071, to Palermo, shows an embolic coil assembly using interlocking clasps mounted both on the pusher and on the embolic coil. U.S. Pat. No. 5,261,916, to Engelson, shows a detachable pusher-vaso-occlusive coil assembly having an interlocking ball and keyway-type coupling. U.S. Pat. No. 5,304,195, to Twyford et al., shows a pusher-vaso-occlusive coil assembly having an affixed, proximally extending wire carrying a ball on its proximal end and a pusher having a similar end. The two ends are interlocked and disengage when expelled from the distal tip of the catheter. U.S. Pat. No. 5,312,415, to Palermo, also shows a method for discharging numerous coils from a single pusher by use of a guidewire which has a section capable of interconnecting with the interior of the helically wound coil. U.S. Pat. No. 5,350,397, to Palermo et al., shows a pusher having a throat at its distal end and a pusher through its axis. The pusher sheath will hold onto the end of an embolic coil and will then be released upon pushing the axially placed pusher wire against the member found on the proximal end of the vaso-occlusive coil.
None of these documents disclose an anatomically shaped vaso-occlusive coil where the loops making up the three-dimensional configuration are not non-overlapping.
In one aspect, the invention includes a vaso-occlusive device comprising at least one substantially linear strand of a vaso-occlusive member wound into a stable, three-dimensional relaxed configuration comprising a plurality of non-overlapping loops, wherein said relaxed configuration self-forms upon release from a restraining member. In certain embodiments, the relaxed configuration of the vaso-occlusive device fills a body cavity or, for example, approximates the shape of sphere. The vaso-occlusive devices described herein can include any number of non-overlapping loops, for example in certain embodiments the device will have between about 6 and 20 loops while in other embodiments the device will have between about 6 and 12 loops. The vaso-occlusive devices described herein can be comprised of a metal, for example, platinum, palladium, rhodium, gold, tungsten and alloys thereof. In other embodiments, the vaso-occlusive devices described herein comprise a stainless steel or super-elastic metal alloy. In still other embodiments, the vaso-occlusive member comprises nitinol.
In other embodiments, any of the devices described herein further include additional filamentary material attached to the vaso-occlusive member. In still further embodiments, the device comprises a deployment tip attached to at least one of the two ends of the vaso-occlusive member. The deployment tip can be, for example, mechanically detachable or electrolytically detachable (e.g., by the imposition of a current on the pusher).
In another aspect, the invention includes a method of occluding a body cavity comprising introducing any of the vaso-occlusive devices described herein into a body cavity (e.g., an aneurysm).
In yet another aspect, the invention includes a method of making a non-overlapping three-dimensional vaso-occlusive device described herein, the method comprising (a) winding a substantially linear strand of a vaso-occlusive member around a winding mandrel, said winding comprising a winding pattern that produces a non-overlapping three-dimensional vaso-occlusive device described herein; and (b) heating the mandrel and vaso-occlusive member to produce said vaso-occlusive device. In certain embodiments, the winding pattern approximates a Figure 8 shape or an hourglass shape. In other embodiments, the winding mandrel is a three-dimensional structure (e.g., approximate sphere, cube, cylinder, tetrahedron). Further, the mandrel may include grooves adapted to fit the substantially linear strand and/or pins on the surface thereof (e.g., a winding mandrel comprising 3 intersecting posts which form a 6 post structure and wherein each post is at approximately 90 relative to the adjacent posts). One or more pins may have the same cross-section (e.g., shape such as round or square, diameter, etc.) or, alternatively, each pin may have a different cross-section.
These and other embodiments of the subject invention will readily occur to those of skill in the art in light of the disclosure herein.